With IRB approval, this was a prospective cohort study of 82 consecutive patients with lumbar and unilateral radicular pain treated with a NRB (1-2 levels, bupivacaine + 60-120 mg methylprednisolone). Each patient had CT or MRI findings of neuroforamen narrowing due to a herniated disc or a disc/osteophyte complex. At baseline they completed the Brief Pain Inventory and the Hospital Anxiety and Depression Scale, which were repeated at one-month follow up. Percent improvement in average daily pain rating was the primary outcome.

N=82, average age= 59 years, 54% female, 46% working, 36% on opioids (n=30), 29% previous spine surgery, average pain duration 6.1 years, average baseline pain 6.1/10. At one month, ANOVA revealed that those NOT on opioids had 27.8% improvement in average daily pain vs. 5.2% in the opioid group (p=.01). The demographic, medical history, and psychological symptoms variables were not different between groups. The findings in the opioid group remained significant after examining the impact of these secondary predictors, as well as non-opioid medications on the ANCOVA model (none of which were significant). The opioid group reported significantly less improvement in activity, walking, work, mood, and enjoyment of activities after the NRB (p<.05).

Concurrent opioid use is associated with significantly diminished response to NRBs at one month. The effects of duration of opioid therapy and dose are being explored. The mechanism by which opioids may decrease the effectiveness of NRBs may be opioid hyperalgesia. Alternatively, motivational/behavioral factors may be responsible, which are reflected by opioid use, i.e., opioid use may be a proxy measure for psychosocial reasons predisposing a patient to a poor NRB outcome.